Process and quality control for automotive laser welding applications

Laser welding applications using CO₂ and Nd:YAG-Lasers are of growing importance for the production of car bodies. Especially for parts influencing the safety of the product, it would be advantageous to control the welding result which is, in practical applications, influenced by many process parameters. In this paper, an innovative process monitoring and quality control system with a closed loop control of the laser output power will be described, which is based on monitoring and evaluating the light emission from the welding process. In contrast to systems which have been developed in the past, the sensors which detect the light emission were integrated into the beam guidance system for CO₂ lasers, and into the laser source for Nd:YAG lasers. The optical set-up of this system, together with the automatic detection of welding failures, will be described, and the results of the system for industrial applications will be evaluated.